Agriculture Reference
In-Depth Information
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M
itigating Drought at a Farm Scale
At a property level, policies for stock, pasture, and crop management tend
to be based on expectations of average climate rather than on an extreme
event such as drought. There is also a degree of flexibility to cope with
the eventuality of extremely dry periods, although there comes a point
when the most economic approach is to deal with drought when it hap-
pens (e.g., Daly, 1994). Strategic and tactical responses to drought dif-
fer according to the type of enterprise, and a variety of information is
synthesized on fact sheets on various state government Web sites (e.g.,
www.dpi.qld.gov.au/drought;
http://www.agric.nsw.gov.au).
Strategies in
nonirrigated cropping lands may include diversification of crops with vary-
ing degrees of drought resistance, sequencing of crops and fallow, or ad-
justing fertilizer application.
If drought results in the failure of a crop, the only alternative is to
either do nothing or to plant a short-season crop. In pastoral lands, the
options are also limited (Bureau of Agricultural Economics, 1969). One of
the most important strategies is to maintain a conservative stocking rate
in most years to reduce forced destocking, conserve fodder, make animals
physically better prepared for dry conditions, and make feed available for
purchase of stock from nearby areas.
A number of computer-based decision-support tools (e.g., Drought Plan;
http://www.regional.org.au/au/asit/compendium/i-06.htm)
have been de-
veloped to help primary producers assess options for drought management
(White and Howden, 1991). Many decision-support tools are based on
farm-scale agronomic models and allow alternative management strategies
to be simulated and tested over a long (approximately 100-year) period.
Results can be expressed as probability distributions to indicate the risk as-
sociated with specific management options and the degree to which ENSO,
for instance, changes this risk. Agronomic models such as GRASP and AP-
SIM (described later in this chapter) have demonstrated the usefulness of
ENSO-based statistical climate forecasts for a range of decisions, including
those linked with drought management in both cropping and grazing lands
(Hammer et al., 2000).
The remainder of this chapter focuses on the broad-scale monitoring
of drought and, in particular, the development and implementation of a
national drought alert system. The system has proven valuable in assisting
the process of objectively allocating drought relief and has the potential
to improve preparation and planning for drought by focusing attention on
emerging drought situations.
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O
perational Drought Monitoring in Australia
Several levels of drought monitoring exist in Australia. The Bureau of Me-
teorology (BoM) monitors drought across the nation from a meteorolog-
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